Inside the Human Body (2011) - full transcript

MICHAEL MOSLEY:
This man is blind.

Yet he can climb
the world's most terrifying peaks.

These fishermen can see underwater
better than almost anyone else on Earth.

And this delightful young girl
is alive and well...

...despite having
just half a brain.

Their stories are part of YOUR story...

...the story of what makes YOU human.

Hidden deep under your skin
is a wonderful inner universe.

A place of raging torrents,

electrical storms...

...and triumph against the odds.



This is a fantastic voyage
through the most extraordinary organism on Earth.

{\fad(2000,0)}Inside The Human Body

Strange as it might seem,
this bizarre-looking creature is you.

Or rather, what you look like
just three weeks after your conception.

This was when your brain was born.

It was the start
of an astonishing transformation...

...as you went from
a small handful of brain cells...

...to the exquisite network
of a hundred billion brain cells

that you carry around inside your head.

We call this transformation... childhood.

It's a remarkable time

that we'll share
with three young girls,

each on the brink
of momentous change.

Baby phoebe is rapidly
growing brain connections



as she discovers her senses.

11-year-old wendy
is learning to speak,

not one,
but 11 different languages.

And stephanie's teenage brain

is pushing her
to explore her wild side.

Together, they reveal
the extraordinary story

of how you built your brain.

It all started
before you were born.

In the womb, you grew 8,000
new brain cells, every second.

By the time you were ready to be born

you had all the brain cells
you'd ever need.

But this baby is about to experience the shock of her life.

Come on, big, big push.
Big push.

Push down.

Don't scream, just push.
Get angry and push down into your bottom.

Come on.
Push.

It's got hair!

What time is it?

- It's, er, about...
- 21:00

This is Phoebe.

As she emerges,
her eyes are dazzled by light.

She's come from a gloomy,
watery world into a bright, noisy room.

It's time for her to meet
Mum and Dad.

Oh, that was...
that was pretty difficult.

- Yeah.
- And hot.

MIDWIFE:
I think we gathered that.

Painful
and...

There is a reason
why it's "labour"!

Phoebe's brain is being flooded
with new sensations.

The chill of the room.

The smell of her dad.

Hello.

And, most puzzling of all,

the strange images that are
pouring in through her eyes.

The lens that lies in the centre of the eye
can't focus on anything for long.

Even so, newborns recognise
their mum's face after just a few hours.

At the back of the eye
is the red plane of your retina.

Here, light from outside shines down

casting images across the surface.

Underneath, these rays
enter a dense forest

of 125 million light-sensitive cells.

These rod cells each detect
just a tiny part of any image.

They send these fragments
to your brain

which has to piece it all together.

Phoebe's rod cells
give her the ability

to see things that move quickly.

They also allow her
to see in the dark.

And incredibly
they started working

when she was still
in her mother's womb.

Your rods are so sensitive

they could detect the dim light that
passed through your mother's belly.

So they were training your brain
to see in black and white

month before you were born.

But in daylight,
the amount of light around

can increase a million fold.

And just like the moment of your birth,
this totally bleaches out your night vision

so a whole new set of sight cells
spring into life, your cones.

You have a richer experience of the world
than most other mammals

because your cones detect not two,
but three different colours.

In one location,
they begin to group together,

causing the retina's surface to bulge.

Year after year,
they continue to rise

creating a volcano-like structure.

It's not until you are four years old
that the mound is finished.

This is your fovea.

It's the only part of your eye
where your vision is crystal clear

and thanks to your cones,
capable of sensing

millions of different colours.

But the complexity
and the beauty of the human eye

is nothing without your brain.

You blink up to 20 times
every minute.

Each blink lingers
for less than half a second.

But add all those blinks of an eye up

and you're living in the dark
for over an hour every day.

Your brain is so good
at filling in the gaps,

that you're not even aware of it.

Your eyes
are an extension of your brain.

They are so adaptable
that you can learn to see

in places where human eyes
normally struggle.

This is the remote Thai island
of Koh Surin.

Home to a group of sea gypsies
known as the Moken.

To survive, they've become
expert underwater foragers.

Finding food underwater is difficult

particularly without goggles.

That's because our eyes
have adapted to see clearly in air.

In water, the world becomes blurry.

As you descend,
light levels drop quickly.

Your eye reacts
by opening the iris

making the pupil larger
and allowing more light in.

The image becomes brighter,

but underwater, a larger pupil
also makes the image more blurred.

But Goon has learnt how to overrule
this automatic reflex

with an astonishing adaptation

seen clearly
with the help of an infrared camera.

Instead of opening his pupils,
he closes them as far as they will go.

This means Goon can see twice as well
underwater as you or I.

Recent studies suggest that any child
can quickly learn this trick.

The Moken show
how well the human brain

can adapt the body
to suit its needs.

This adaptability
has enabled our species

to thrive on all seven
of Earth's continents.

Hey!

But at three months old,

Phoebe's brain is still hopeless
at pretty much everything.

It can tell her mouth to suck
but can't feed itself.

Can't maintain body temperature.

Can't even control
when she goes to the loo.

I now am utterly and totally responsible
for another human being

who has to take priority
over my life in everything.

She has to come first,
otherwise she can't survive.

Phoebe is so very helpless because
her brain is still getting organised.

Bit by bit,
her brain is creating her mind.

This remarkable time lapse
shows living brain cells

sending out tendril-like arms,
which connect with each other.

Each of Phoebe's
hundred billion brain cells

will on average make
10,000 different connections

and we can follow this
on the outside.

Oh, I've gone away!

At six months, Phoebe thinks
that when she can't see someone,

they vanish from the world entirely.

I'm here.

Ya-a-a-a-a-ay!

Watch Phoebe's face
as Charlotte hides.

- Now you don't see me.
- She immediately loses interest.

Where's Mummy gone?
Where's Mummy gone?

- Shall I come back?
- But when her mother reappears,

- I've come back!
- her delight is obvious.

Yes, I am.

Going to come back,
I'm here.

- Where's Mummy gone?
- Three months later,

and Phoebe's brain has now learnt

that just because something is hidden
doesn't mean it's disappeared.

Here I am!
Yes!

A childhood game of peekaboo
has helped her build connections

that will stay with her
for the rest of her life.

And the longest connection
Phoebe's brain will ever make

is the one between her head
and her toes.

Remarkably, the connection
between your head and your toes

won't be fully mature
until you are three years old.

Long before that,
your brain just can't resist

the urge to take its first big step

as you try to walk.

Learning to balance
and coordinate your body

is so complex
that the area of your brain

devoted to this one task
involves as many cells

as the whole of the rest
of your brain put together.

Some people learn how to walk
sooner than others.

But there is a place where people

pull off this feat
sooner than anywhere else.

This is Kaumba.

She is mother
to a baby girl called Kosini.

They live in Rhumsiki.

A tiny village in the remote
northern highlands of Cameroon.

Here, mothers are keen
to get their babies off their backs

and walking as soon as possible.

Ever since Kosini was a month old,

her mother has repeated
the process of "Kitete"

which means to make jump.

Every day, she takes hold
under the arms and bounces her.

Kosini responds with
a kind of stepping reflex.

You had this reflex, but it disappeared
after a couple of months.

But here in Rhumsiki,
this daily encouragement

means that the reflex remains and
gradually develops into mature walking.

Now she's seven months old,
it's time for Kosini

to try and stand up by herself.

So her mother sets about
another ritual practice.

She washes her
with a warm herbal liquid.

This seems to stimulate her legs,
preparing them for walking.

The leftover warm leaves
are laid on the ground

and Kosini is placed on them.

It's uncomfortable

and she soon wants to get off

giving her the gentle encouragement
she needs to use her legs.

These rituals seem to be accelerating

the connections that Kosini is making
between her brain and her feet.

But before you can stand up
for any length of time,

there is a strange part of your body
that your brain must learn to understand.

This cavern is buried
deep inside your head.

It's part of a labyrinth
of twisting tunnels

completely submerged in fluid.

The tunnels are the three great loops
of your semicircular canals.

Inside each loop there is
a saddle-topped fleshy mountain -

your crista.

The mountain slopes are covered
in a thick forest of tiny hair cells.

For the moment, they lie still.

But this inner sea
never remains calm for long.

As you move your head,
it generates a shock wave

which races through the tunnel
and pummels the mountain.

On its flanks, the hair cells
are thrown about in the turbulent waters.

The pressure builds

until electricity flows

creating a powerful electrical current.

All this activity going on
inside your semicircular canals

creates your sixth sense -

your sense of balance.

To walk, your brain has to sense

when you are overbalancing
to one side

and then instruct your body

to shift your weight
back to the centre.

All of this has to happen
within a fraction of a second.

To begin with,
it's a real struggle.

But Kosini's half-brother, Tisema,
is already a master of bipedalism.

He is just ten months old.

At his age, most children
are shuffling around on their bottoms.

From now on

and for the rest of Tisema's life,
walking will be automatic.

By the age of one, your brain has made
over 500 trillion connections.

So many that your brain can cope with
almost anything that life throws its way.

Angelina is a rather
remarkable one-year-old

because she was born
with just half a healthy brain.

She has a rare disease

which affects the blood vessels
on the right side of her head.

She's a happy, active little girl,
but every now and then...

Angelina?

Angelina?

Angelina?

Angelina?

You all right?
OK?

Angelina's having what we call
a complex vocal seizure.

As you can see, she was very very active
and now she's gone very distant.

One indication is that her head lags.

She's slightly heavy in her breathing.

Angelina has a rare condition,
Sturge-Weber syndrome.

This one is going on quite a bit, isn't it?

Angelina?

Angelina?

Her parents, Lisa and Stephen

have had to deal with her seizures
ever since she was born.

Angelina's brain scans
show the cause, abnormal blood vessels.

Seen here in white
on the right side of her brain.

But they also show that the left half
of her brain is perfectly healthy.

There is a treatment
for her condition.

But it involves radical surgery

cutting off the damaged half
of Angelina's brain.

We're in a position we don't know what
we've got to face after this operation.

I pray to God
she comes back to us at all,

but what she does come back as,
we accept.

The surgeon who must navigate
his way through Angelina's tiny brain,

is Mr William Harkness.

We've lifted the bone flaps
so we've made our trap door in the skull.

And now we're beginning
to see the brain.

It seems impossible
that you can disconnect

half of someone's brain
and expect them to recover.

Yet that is exactly what the surgeons
are hoping will happen.

The brain does adapt
at this age of life,

we would expect most of the functions
to transfer to the other...

...other side of the brain.

It takes four hours of micro-surgery

to find the bridge between
the two sides of Angelina's brain.

And this is what's called
the corpus callosum

which connects one side
of the brain to the other.

Now, he cuts through it.

Angelina's healthy brain
is finally free

from the disruption
caused by the damaged right half.

Hopefully, if this child
becomes seizure-free,

I think that we will have given her
the best opportunity for the future,

because the type of epilepsy
that she had

clearly is life-threatening.

Angelina?

- She's so sleepy.
- Yeah.

I haven't even given her a kiss yet.

- Haven't you?
- No. Come here, lovely.

Come on, my darling.

Hello, sweetheart.

Who's a strong little girl, eh?

Who's Daddy's strong little girl?

You have a nice dream.

All her parents can do
is wait and hope.

It was essential for Angelina
to have the operation at this age,

because after your first birthday
your brain loses some of its flexibility.

While there's still room
for plenty of development,

there's less scope
for fundamental change.

But as your young brain starts to explore
the world from its new, lofty position

there is an immediate
and rather wonderful consequence.

That's because walking releases
two powerful natural tools -

your hands.

I've kind of developed a skill with
my hands that when I touch things,

I get information from it.

A bit more than an average human.

From a young age,
street magician Dynamo

has been fine-tuning
the control of his hands.

If I put a pack of cards
into your hand,

you'd just feel
the edges of the cardboard, right?

Whereas I can actually feel
how many cards there is in my hand.

I've built up, you know,
a sense that allows me to do it.

I give these cards...

His hands are so nimble
your brain cannot keep up with them.

Just name any playing card.

Five of Clubs.

- Five of Clubs, yeah?
- Yeah.

- Are you sure that's the one you want?
- Yeah.

- Yeah? Definite?
- Yeah.

OK.

I've got some cards in my pocket.

What I forgot to mention was that one of
the cards inside this deck is upside down.

OK.

Yeah?
Look at this.

- Just one card upside down there, yeah?
- Yeah.

- What card did you say?
- Five of Clubs.

Turn that over.

No!

What?

Your hands' versatility springs from
a mixture of strength and sensitivity.

At the tip of each finger

is the densest collection
of nerve receptors

found anywhere on your body.

Feeding your brain with information

about the temperature, pressure
and vibrations of anything you touch.

They're so sensitive
they can detect lumps and bumps

less than a 100th
of a millimetre across.

Yeah, just reach in
and pull out any card.

Show it to them.

I'm going to put it about half way down.
A few more. That's about halfway, right?

- Yeah.
- Yeah.

Just put your hands out, please.

I'm going to focus on the car, right, watch.

Oh!

That was incredible Dynamo

- You are the man.
- That was amazing.

Dynamo, I'm telling all my friends.

- Oh, do it.
- I'm telling all my friends.

- Brilliant.
- Group hug.

Thank you so much.
That was amazing.

Your hands allow your brain
to reach out and change the world.

As a result, our species is the only one
to have built a civilisation.

Standing upright and walking

releases the potential
of your wonderful hands.

And it's followed
by another milestone.

An ability that is
uniquely human -

the ability to talk.

When I was one,

I spoke Vietnamese only, like...
it was just like baby words.

When I was two, I spoke English,
Vietnamese, Spanish and Chinese,

so four languages
when I was two years old.

Well, I started learning them.

From an early age, Wendy Vo's brain
has been bursting with languages.

She hasn't stopped
at just four languages.

Wendy spends an hour every week

talking to a range of different
people in their native tongues.

I am Winita from India,
and I teach Wendy Hindi.

HINDI DIALOGUE

My name is Rashida
and I teach Wendy Arabic from Yemen.

ARABIC DIALOGUE

And I teach Wendy Spanish.

She speaks Spanish a lot better
than some Hispanic kids do.

WENDY SPEAKS SPANISH

At the Russian languages,
she is very good.

RUSSIAN DIALOGUE

Portuguese...

PORTUGUESE DIALOGUE

She is at the top because she can
switch very... in few seconds,

from one language to the other ones.

FOREIGN DIALOGUE

And she can think, speak, write.
It's unbelievable.

Vietnamese, English, Spanish, Chinese,

French, Japanese, Hindi, Arabic,
Russian, Cantonese and Portuguese.

Add them all up
and Wendy has

11 different voices
packed inside her head.

But speaking is only
half the story.

For meaning to fly
from one person to another,

the words have to travel
deep into your body.

Inside your ear, sounds set off
a complex chain of events.

They enter as pressure waves

which push, pull your eardrum
making it vibrate.

On the other side of the eardrum,

these vibrations
set a series of bones jiggling.

They end with the smallest bone
in your entire body,

called the stirrup.

It is smaller than a grain of rice.

These bones allow you to hear.

If a sound is too loud,

a muscle pulls the stirrup away
from the most sensitive parts.

Temporarily, at least,
you go a bit deaf

but the rest of your ear is protected.

Beyond the stirrup
is a fluid-filled cavern, your cochlea.

The incoming sound waves

tickle clumps of tiny
hair-like sensors on the floor.

tickle clumps of tiny
hair-like sensors on the floor.

tickle clumps of tiny
hair-like sensors on the floor.

tickle clumps of tiny
hair-like sensors on the floor.

tickle clumps of tiny
hair-like sensors on the floor.

tickle clumps of tiny
hair-like sensors on the floor.

tickle clumps of tiny
hair-like sensors on the floor.

tickle clumps of tiny
hair-like sensors on the floor.

tickle clumps of tiny
hair-like sensors on the floor.

tickle clumps of tiny
hair-like sensors on the floor.

tickle clumps of tiny
hair-like sensors on the floor.

tickle clumps of tiny
hair-like sensors on the floor.

These begin to dance
to the sounds of the world outside.

You have 30,000 sensors.

Each picks out
a different part of the sound

and sends it straight to your brain.

The cochlea is most sensitive
to the sounds of another person's voice.

SPEAKS RUSSIAN

RUSSIAN DIALOGUE

Finely-tuned ears
and a wonderfully versatile voice

have allowed humans to inven
over 7,000 different languages.

And each of us, as we grow,

pick up over a thousand
new words every year.

By your early teens

you have a working vocabulary
of over 10,000 words

as you head towards
the brain's next challenge... puberty.

Stephanie Bean is 14 years old

and like all teenagers,
she's maturing, physically.

We really don't talk about
the puberty thing really.

I don't know, some girls
think it's embarrassing.

- Hey.
- Hey.

Come and spit out of your gum!

Like the rest of her teenage friends,
Stephanie's brain is maturing too.

And the way it does this is bizarre.

During her teenage years,

she will lose 40% of the connections
she spent more than a decade building.

This extraordinary image is made
from hundreds of teenage brain scans.

It shows how
as the brain matures,

the areas which are packed with connections,
coloured red and yellow,

make way for areas
that contain far fewer, coloured blue.

The brain is pruning away
the connections that it doesn't need.

Scientists believe
that this leads to

more efficient
and faster thinking.

But perhaps the most
puzzling change during puberty,

is that your brain seems determined
to travel a dark road,

to risk-taking and recklessness.

As well as being a cheerleader,
Stephanie Bean has another hobby.

She is also the world's
youngest stock car racer.

I started racing stock cars
when I was ten years old,

so I've been racing them
for four years.

She's competing
on the Winchester Speedway

also known as the world's
fastest half-mile.

At 37 degrees,

these are the steepest curves
in American motor sport.

It's pretty awesome because
whenever you go round, it's like,

you get all that speed in you and

just builds up and
it's like I want to go.

Stephanie is prepared
to take risks

that many of her adult
competitors will not.

One reason is that
part of her teenage brain

is releasing neuro-chemicals
that encourage risky behaviours.

There will probably be about 20 cars
out there, going like, around 90...

...to 100 miles an hour

very close, like inches away
from the wall.

Whenever she takes a risk,
her teen brain rewards her

with a much stronger natural high
than her grown-up competitors.

Whenever a car's next to me,

it just makes me wanna go
even more faster.

If there's a gap, then,
you know, take chances.

It's her brain's accelerator pedal,
pushing her to take risks.

Go Stephanie, go!

But the scan of the developing brain
reveals something else.

The last part of the brain
to turn blue and mature,

is the bit at the front

which thinks through
the consequences of taking a risk.

Stephanie's isn't fully mature,
so even when she recognises

that something is dangerous,
she will probably do it anyway.

But why are teenagers
wired to take risks?

One theory is -

it's to encourage you
to try lots of new things

before you settle down
into adulthood.

Ever since that time, long ago,
when you were just a tiny embryo

you've been busy nurturing
your brain cells.

You've assembled so many

that their numbers now rival
the hundred billion stars

that populate our galaxy.

And this vast, beautiful network
has been shaped

by the kaleidoscope of sights,
sounds and feelings

that you've lived through.

Now, finally,
after 20 years, it's done.

You are the proud possessor
of an adult brain.

Until recently, scientists believed

this was pretty much
the end of the brain's story.

That from then on it was just a slow,
gentle decline into old age.

But we now know that your brain retains
that wonderful child-like ability to learn

throughout your life.

Adventurer, Erik Weihenmayer,
is a striking example

of how well a middle-aged brain
can respond to new challenges.

There's that step again, Erik.

Erik went blind
when he was 13 years old.

Every week, you know, I would wake up
with different levels of vision

because my retinas
were splitting away from my eyes.

Today, Erik with his friend, Greg Childs,

is going to attempt to scale
Utah's formidable Castleton Rock.

It's Erik's first climb here.

To help him, he has brought along
an impressive bit of new technology.

I don't know if you've seen this.
This is a brain port device.

This is the camera
on these sunglasses here.

The camera picks up images

and sends a feed
to a computer on Erik's hip

which translates the images into a
low-resolution picture of the world.

These blocky images are then sent

to one of the most sensitive parts
of Erik's body.

This is the tongue display.

On the surface are hundreds
of tiny electrical stimulators.

If the camera sees a distinct outline,

a corresponding line of stimulators
buzz away, tickling Erik's tongue.

I can feel each dot, and together
they create lines and shapes, and -

and, ultimately, images
that my brain then reinterprets

as the space around me.

Three decades
after he lost his sight,

the visual part of Erik's brain,
his mind's eye, is back in action.

Except now,
he's not seeing with his eyes.

He's seeing with his tongue.

Is that sight?
Well, kind of, you know,

because I think seeing is more
in your brain than in your eyes.

In rock climbing, most of the risk
is taken by the lead climber.

Greg led most of the tower.

He's making sure, you know, that if
I fall, I'm not going to fall too far.

Ah! Oh. OK!

Well, sometimes I like
to lead the rock face too.

That's really fun for me, because I'm now
the first person going up the rock face,

I'm taking the risk.

- Last pitch to the top.
- Excellent.

OK, are you ready?

Erik is feeling so confident
with the brain port device

that he decides
to lead the final push.

And now I'm Greg's safety,
for me, you know, that's a real honour,

being blind and still being able
to be a real part of the team.

You pop over this lip
and it's completely flat

and the wind just gusts
in your face.

And you're up there
on this flat tower,

a thousand feet
above the desert floor.

- It's a privilege.
- I know.

This is totally beautiful.

Erik is a great example
of the brain's astonishing ability

to remodel itself.

It's this that makes us
so wonderfully adaptable.

And six months on
from the operation to split her brain,

it's this adaptability that is giving
Angelina the chance to flourish.

It's just wonderful to see now

that the development is just
coming on in leaps and bounds.

Are you going to come to Mummy?
Come to Mummy. Good girl.

To hear her start to talk,
start to walk,

it's just absolutely amazing.

...for you?
Say "hello".

Stone, paper, scissors, shoot.

Whatever your age,
if you continue to stretch your brain,

you can be sure
it will rise to the challenge.

Stone, paper, scissors, shoot.

This is adventure,
you know, this is total adventure.